1. Field of the Invention
This invention relates to a terminal for connection by ultrasonic wave, which is to be conductively connected to a covered wire by ultrasonic wave energy, and a structure therefor, wherein a covered wire is to be connected to a terminal by ultrasonic wave energy.
2. Description of Relevant Art
This kind of art has been disclosed in, for example, Japanese Patent Publication No. 7-70345. FIGS. 1A-1D illustrate the art. FIG. 1A shows a first member 1 and a second member 2. Both the members 1, 2 are formed of material (plastic) which can be fused by ultrasonic vibration. The first member 1 contains groove portions 3 and the second member 2 includes protrusions 4 which engage the groove portions 3.
FIG. 1B shows a terminal 7 contained in a groove portion 3 and a covered wire 8 placed on the terminal 7. On a bottom face of the groove portion 3 are small concave portions 3a and on a top face of the corresponding protrusion 4 are provided small protrusions 4a which engage the small concave portions 3a.
According to this art, as shown in FIG. 1C, the terminal 7 is contained in the groove portion 3 and the covered wire 8 is placed thereon. After that, the second member 2 is mounted on a top face of the first member 1 so that the protrusions 4 are inserted into the groove portions 3. Then, ultrasonic vibration is applied while a pressing force is applied between the first and second members 1, 2, so that a cover portion of the covered wire 8 nipped between the protrusion 4 and the groove portion 3 is melted thereby making the core elements of the covered wire 8 into conductive contact with the terminal 7. At the same time, the first and second members 1, 2 are welded to each other by ultrasonic fusion so that an integrated connection structure as shown in FIG. 1D is obtained, whereby core elements of the covered wire 8 are connected to the terminal 7.
However, according to the aforementioned art, as shown in FIG. 2, the melted cover portion 8b escapes into gaps between the groove portion 3 and side faces of the protrusion 4. At this time, some of the core elements 8a escape sideways together with the melted cover portion 8b, so that excellent conductive contact between the core elements 8a and terminal 7 is lost.
As a countermeasure, as shown in FIG. 3, a method of eliminating the gap between the groove portion 3 and the protrusion 4 can be considered. However, if the side faces of both the groove portion 3 and protrusion 4 are in contact with each other, ultrasonic wave is not transmitted excellent to a target position (covered wire 8 on the terminal 3) so that processing efficiency may drop. Further, because escape place of the melted cover portion 8b exists only in the length direction of the groove portion 3, engagement between the first and second members 1, 2 becomes incomplete, so that excellent conductive contact between the core elements 8a and terminal 7 may be lost.